As an example of a system for storing serial data in memory, consider a multiport memory having a random access port and a serial access port. Such a memory finds application for example in computer display circuitry and digital communication network circuitry. The parallel port is conventionally coupled to a processor for read and write access. The serial port is conventionally coupled to a peripheral device such as a video display or a network transceiver for read and write access. In either case the multiport memory performs serial to parallel conversion for a serial stream of data written into the serial port so that received serial data is accessible in parallel via the random access port. Data transfer at the serial port is at a rate much faster than data transfer at the parallel port, hence data rate conversion is also accomplished.
To the designer of display systems and network systems, high serial data rate is of critical importance. A limited serial data rate to a display ultimately limits the display refresh rate and the amount of data that can be revised. In many systems, the quantity of data to be displayed is, therefore, limited, consequently, reducing the display resolution. Without sufficient resolution, some computing tasks are not feasible; especially tasks involving measurement, rendering of the displayed image onto film, and projection of the displayed image. For similar reasons, data rate is critical to network capacity and efficiency. When serial data rate is limited, fewer messages can be communicated and message length is reduced. Consequently, transmission of network control messages and retransmission of messages to eliminate transmission error become inefficient.
In many applications beyond displays and networks, it is desirable to support a high serial data rate into a memory device coupled to a processor. Many mass storage devices require data to be accessed serially. Measurement and control functions in process control systems often involve conversion between parallel and serial data representations. Without increased data rate capability, the advances in data processing, communication, measurement, mass storage, and display technologies are unavailable to the systems designer because the serial data rate stands as a systems bottleneck.
In view of the problems described above and related problems that consequently become apparent to those skilled in the applicable arts, the need remains for circuitry to write serial data at a high data rate into the serial port of a multiport memory.